As per the description, I understand that you are experiencing the issues with the numeric keys. This issue might occur due to hardware corruption or driver corruption.
Let’s try to identify the actual cause and troubleshoot accordingly.

However, before we proceed I would require some more information to assist you better.

1. What is the make and model of the computer?

2. Does the issue occur with a different keyboard?

3. Are you experiencing this issue with a particular program or with all the programs?

I would suggest you to open On-Screen Keyboard and check if the numeric keypad works fine.

If the issue doesn’t persists with the On-Screen Keyboard,
then check all the keys of the keyboard and check if there is any key left pressed, damaged or have dust in it.

If all the keys are fine, then try to use the same keyboard with the different working computer and check if you are experiencing the same problem. This will help determine if the problem is the keyboard or the computer.

You may also try to use the different keyboard and check if it works fine.

If the problem goes away with another keyboard and occurs on the other computer with this keyboard, then the keyboard is defective and needs to be replaced.

Hope the information helps. Let us know if you need further assistance with Windows related issues. We will be happy to help.

If the issue still persists, then try the next method and check the issue.

Method 2: Check the issue in Safe Mode and perform a Clean Boot.

Step 1: Boot the computer in Safe Mode and check if the issue persists.

In Windows, we can start the computer in different advanced troubleshooting modes to find and fix problems on the PC. One of such troubleshooting mode is Safe Mode. Here we start Windows with a minimal set of drivers and services.
Please refer to the steps in this link to boot the computer in safe mode:

If the numeric keypad works fine in the safe mode, then you may boot the computer back to the normal mode and then perform a clean boot to check if the issue is caused by any software conflicts. You may please note that performing
a clean boot does not fix the actual issue. It just helps us in identifying the root cause of the issue.

Step 2: Perform a Clean Boot and find out which application/service is causing this issue.

A clean boot helps to eliminate software conflicts and to determine what is causing the problem. Perform a clean boot on the computer by following the steps given in the link:

Follow all the steps given in this link and try to figure out the application or service causing this issue. Please note that performing a clean boot does not fix the original issue. It just helps us in understanding the cause
of the issue.

Note: After you have finished troubleshooting, refer to the article
“How to reset the computer to start as usual after clean boot troubleshooting” for Windows 7, given under the section “More Information”
to reset the computer to start as usual from the above link.

Hope this information is helpful. Please feel free to reply in case you face any other issues with Windows in future.